RFC: HW watchpoints and single stepping for ARMv6/v7

[Zbigniew Bodek]

Hello Russell,

That will be a good sign if it doesn't explode (if you see undefined
instruction on boot then there's something wrong).
More extended description what you can do with HW watchpoints is in
this thread. For example you can check:
https://lists.freebsd.org/pipermail/freebsd-arm/2015-November/012724.html

Best regards
zbb

2015-11-30 19:03 GMT+01:00 Russell Haley <russ.haley at gmail.com>:
> Cool. I have a hummingboard (iMX6). Do I need to know what I'm looking for
> or am I just making sure it doesn't explode?
>
> Russ
>
> On Mon, Nov 30, 2015 at 6:41 AM, Zbigniew Bodek <zbb at semihalf.com> wrote:
>>
>> Hello again,
>>
>> It seems that this is the last chance to test this patch on other
>> platforms than Rpi, Arndale and Pandaboard.
>> Please check out this https://reviews.freebsd.org/D4037
>> I will be grateful if you had  a chance to test this on something else
>> than the above mentioned.
>>
>> Best regards
>> zbb
>>
>> 2015-10-31 17:21 GMT+01:00 Zbigniew Bodek <zbb at semihalf.com>:
>> > Hello again,
>> >
>> > I should have post some more information about testing this patch. Here
>> > it goes:
>> > ------------------------------------------------------------------
>> > One can enter kernel debugger by one of those:
>> >
>> > press: ~, ctrl + b
>> > or
>> > type: sysctl -w debug.kdb.enter=1
>> >
>> > You can then set a HW watchpoint on any memory location at <address>
>> > by invoking following command in KDB:
>> > db> hwatch <address>, <size>
>> >
>> > <size> parameter is optional, the default is 4.
>> >
>> > To display watchpoints:
>> > db> show watch
>> >
>> > To remove watchpoint:
>> > db> dhwatch <address>
>> >
>> > Press "c" to continue.
>> >
>> > ------------------------------------------------------------------
>> > While in KDB you can step through the kernel code using "s" BUT you
>> > need to apply a dependent patch: https://reviews.freebsd.org/D4036
>> > otherwise you will cause the kernel panic.
>> >
>> > Thanks again
>> > zbb
>> >
>> > 2015-10-30 17:25 GMT+01:00 Zbigniew Bodek <zbb at semihalf.com>:
>> >> Hello,
>> >>
>> >> We would like to add HW watchpoints and HW single step support to ARMv6
>> >> kernel.
>> >> Please check this review: https://reviews.freebsd.org/D4037
>> >>
>> >> Since there are differences between debug architectures on ARM (v6,
>> >> v6.1, v7, v7.1) I would like to ask for some testing on your machines.
>> >> I was able to test this on Pandaboard and Arndale but please check
>> >> whether this works on your targets as well.
>> >>
>> >> Rise a red flag if you see any issues or in worst case scenario -
>> >> "undefined instruction" error.
>> >>
>> >> Best regards
>> >> zbb
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>
>